1. Field of the Invention
The invention relates generally to a motorized assist device for raising and lowering the lid of a cooking vessel, such as a cooking vessel on a fryer. In particular, the present invention is directed to a motor assist device including a lifting lid mounted on a supporting brace and a monorail lifting device including a monorail having a receiving bracket for receiving a monorail mounting bracket positioned on the supporting bracket and automatic or manually assisted means for raising and lowering the lifting lid along the monorail.
2. Description of Related Art
A large capacity cooking apparatus or deep fat fryer may comprise a vat or cooking vessel of a sufficient size to receive a wire basket or tray carrier, in which a food product to be cooked is held. The basket or tray carrier is submersed in a cooking medium, such as melted shortening or cooking oil, which is contained in the cooking vessel. The cooking vessel may be closed by a lid which makes a seal with an upper edge of the cooking vessel. Alternatively, a large capacity cooking apparatus may be of an open-well design. In such open-well cooking apparatus, the lid of the cooking apparatus may be an open frame permitting direct access to the cooking vessel and to the food products submersed therein. The frame may support a wire basket for holding food products or a food tray carrier for carrying a plurality of trays containing food products. Although the frame may not form an air-tight seal with the upper edge of the cooking vessel, the frame may reduce spillage and splashing of a cooking medium from the cooking vessel during cooking.
Various types of automatic mechanisms exist for opening and closing the cooking vessel lids. Vertically shiftable rod means for raising and lowering the lid are described in U.S. Pat. No. 3,187,664. U.S. Pat. No. 3,608,472 describes raising and lowering the lid through the use of jack screws or the like. U.S. Pat. No. 3,821,925 describes the use of a geared bar or rack-like system for raising and lowering the lid. U.S. Pat. No. 3,563,158 describes hydraulic cylinders used to raise and lower the vessel lid. In some instances, known mechanisms also may be used to hold the lid down and in place, for example, during the pressurized operation of the cooking apparatus.
U.S. Pat. No. 4,930,408 describes a lid provided with a substantial locking mechanism to maintain the lid in its seated, closed position during that part of the cooking cycle in which the cooking vessel is pressurized. The lid is raised and lowered manually, but is provided with a counterbalance system, so that the operator need not contend with the full weight of the lid. Nevertheless, this system still requires some strength on the part of the operator and is more difficult for the smaller or less strong operator to handle.
In a known configuration, the lid lifting assembly includes a support frame vertically oriented and secured to a rearward end of a pressure cooking apparatus. This configuration is described in U.S. Pat. No. 5,402,712, the disclosure of which is incorporated herein by reference. A support frame includes a pair of vertical guide rails, each having a U-shaped cross-section and opening toward each other. The guide rails are joined together at their upper and lower ends by top and bottom horizontal frame members. The front, rear, sides, and top of the support frame may be enclosed by stainless steel panels forming a lid lifting device housing, which comprises a portion of a cooking apparatus cabinet or a cooking apparatus transfer cart. A carriage is mounted vertically within the support frame. The carriage has wheels or rollers which are adapted to be received within the support frame guide rails. Consequently, the carriage may be positioned vertically within the support frame. A pair of horizontal arms is affixed to the carriage. The arms extend from the carriage toward the cooking vessel lid through vertical slots in the stainless steel panel covering the front of the support frame. The cooking vessel lid of the pressure cooking apparatus is mounted on these horizontal arms.
A cable drum is driven by an electric motor mounted on the top horizontal frame member. In a further known configuration, a pair of cables is provided, each cable having one end attached to the drum and the other end attached to the carriage. One of the cables may be slightly longer than the other and, consequently, does not bear the weight of the carriage. The longer cable serves as a back-up cable if the primary cable fails. The drum is rotatable in a first direction by the electric motor to raise the carriage within the support frame and, consequently, raising the carriage arms and the lid therewith. The drum is rotatable in the opposite direction by the electric motor to lower the carriage within the support frame and to lower the arms and lid therewith. In this manner, the lid of the pressure cooking apparatus may be shifted between its lowered position seated upon the upper edge of the cooking vessel and its raised position.
In another known configuration, the cooking vessel lid may be manually raised and lowered with the assistance of a counterbalance weight supported in the lid lifting device housing. With the assistance of a locking device, the cooking apparatus lid may be manually lifted and supported at various heights. Moreover, the use of a counterbalance weight has been combined with the use of an electrical motor to create a manually assisted raising and lowering means.
In a pressure cooking apparatus, the food product is cooked for the desired length of time under both elevated heat and pressure. Following the cooking cycle, an operator may relieve the pressure in the cooking vessel and then may open the lid in order to remove the wire basket or tray carrier or simply remove the food product from the wire basket or from the trays on the tray carrier. Because such lids must be of sufficiently heavy construction to withstand the pressure within the cooking vessel during the cooking cycle, it may be difficult for some operators to lift the lid to load or unload the cooking apparatus, or remove the wire basket or fryer tray carrier. To overcome this problem, operators have employed various types of automatic mechanisms for opening and closing the cooking apparatus lid. In some instances, these various mechanisms are used to additionally hold the lid down and in a sealed position during the pressurized operation of the cooking apparatus.
Some known lid raising and lowering mechanisms require powerful power train means. Moreover, some of these mechanisms are positioned at the sides of or around the cooking vessel making access to the cooking vessel for loading and unloading and for cleaning difficult or awkward, or both. In addition, some of the raising and lowering means are sufficiently complex to require a skilled operator. Moreover, the more complex and the more exposed the raising and lowering mechanism, the more susceptible the mechanism is to the adverse effects of dust, dirt, and cooking medium residue.